https://www.borehamwoodtimes.co.uk/sport/national/18312075.anthony-joshuas-world-title-fight-kubrat-pulev-delayed/:
"Promoter Eddie Hearn has admitted Anthony Joshua’s next world heavyweight title defence against Kubrat Pulev could be pushed back a month to July."
I think July is being optimistic.
A huge number of different events are going to get cancelled and competition for venue space when things die down is going to be intense.
That said, the boxing event is likely able to pay more than most other events, so it's still possible.
Gives Anthony Joshua an even better chance anyway, since Pulev will be another month older.